/*
 * Copyright (c) 2008 Golden T Studios.
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
package com.golden.gamedev.engine.timer;


/**
 * A utility class to calculate timer frame per seconds (FPS) in convenient way. <p>
 *
 * How to use :
 * <pre>
 *    FPSCounter counter;
 *
 *    // game loop
 *    while (true) {
 *       counter.getCurrentFPS(); // returns current fps
 *
 *       counter.calculateFPS();  // calculating fps
 *    }
 * </pre>
 */
public class FPSCounter {

	private long	lastCount;		// last time the fps is counted
	private int		currentFPS,		// the real fps achieved
					frameCount;


 /****************************************************************************/
 /******************************* CONSTRUCTOR ********************************/
 /****************************************************************************/

	/**
	 * Creates new <code>FPSCounter</code>.
	 */
	public FPSCounter() {
	}

	/**
	 * Refresh the FPS counter, reset the fps to 0 and the timer counter to
	 * start counting from current time.
	 */
	public void refresh() {
		frameCount = 0;
		lastCount = System.currentTimeMillis();
	}

	/**
	 * The main method that calculating the frame per second.
	 */
	public void calculateFPS() {
		frameCount++;
		if (System.currentTimeMillis()-lastCount > 1000) {
			lastCount = System.currentTimeMillis();
			currentFPS = frameCount;
			frameCount = 0;
		}
	}

	/**
	 * Returns current FPS.
	 *
	 * @see #calculateFPS()
	 */
	public int getCurrentFPS() {
		return currentFPS;
	}

}